In recent years it has become increasingly common to monitor groundwater for evidence of pollution. This involves positioning a monitoring well in the suspected area and routinely extracting samples from such wells for laboratory analysis. It is critical the sample be extracted in a manner that will eliminate any possibility of contamination.
The sampling device is conventionally referred to as a "bailer" and comprises an elongated tube having at least one opening for entry of the water sample into a collection chamber. A valve or other mechanism is also provided to trap the water within the collection chamber after sampling.
Prior art bailers are rather complicated in design and must be carefully cleaned after use to prevent contamination of the samples. As a result, it has become common in the industry to employ disposable or "throw-away" bailers that are discarded after a single use.
Throw-away bailers are often manufactured from inexpensive and lightweight materials such as plastic. The use of plastics or other low density material in bailer construction has heretofore required the addition of a weight that enables the device to sink within the fluid being sampled. Typically, such weighing has involved the addition of metal to the bailer. For example, U.S. Pat. No. 4,050,315 to Markfelt discloses a chamber filled with lead shot positioned at one end of a bailer. It is also known to incorporate flanges within the inside wall of the bailer tube for securing a coated steel nut or metal washer.
As is apparent, a bailer that requires supplemental weights raises manufacturing expenses and renders the device difficult to recycle. More significantly, the incorporation of a reactive metal material within the bailer increases the likelihood of contamination to the sample. While these prior art devices are suitable for certain sampling applications, they are not acceptable when highly accurate sampling is required.
A need has therefore existed in the art for a throw-away bailer device constructed from an inert materials that does not require extrinsic weighing attachments.